While investigating in my users accounts, i found one account which has a strange way of working.Most of the messages placed in the junk folder have scores below the limit of 6.6 and even with negative scores and even some including autolearn=ham in the header.I don't understand how and why those messages fall in the junk folder. Furthermore it happens only for one account out of 150.

I analyzed the logs, but even though I see the scores, I don't see when the sorting of messages is made between Inbox and Junk.

In fact I would like to know what is the element of zimbra that ultimately places a message in the Junk folder of a mailbox. Is it Amavis, Spamassassin, Postfix ?

The most likely reason is that you've given no details of the exact problem nor whether you've checked if that user has any filters on their account (or their mail client, if they use one) that may be causing the problem. You also haven't provided any information about the exact headers that are in those 'junk' emails nor whether you've made any changes to your anti-spam system and if so, what changes they are.

I'm sorry but I thought i had given enough details.If I didn't give more informations it's because my server and this account are in a standard state.

So i will be more precise.If i don't understand, it's because my user hasn't any filter configured. The user uses only the zimbra webmail.My zimbra server is configured nearly as "out of the box" except for some scores that have been modified to amplify the impact of Bayes.I explained that the headers don't match the junk classification as most of them have a negative score.

And the most important question I asked was : I would like to know what is the element of zimbra that ultimately places a message in the Junk folder of a mailbox. Is it Amavis, Spamassassin, Postfix ?

So is there someone who could explain me how a message that should obviously be ham can land in the junk folder and only for one account ?